SC Deck height

[gtihop]

I measured the deck height on a 3.0 engine as being .047 in using the caliper method on the side of the cylinder. Then used the solder method as described in Wayne's book and came up with .067 inch. Does this sound right? No case machining has been done, original thickness base gasket was used (.24mm).

[Eagledriver]

Your first measurement is deck height. Your second measurement is cylinder head to piston clearance. They both look good to me for a stock engine.

-Andy

[mb911]

I measured a stock sc yesterday at .075 (inch) so I wonder am I crazy?? I guess my post has no real value but to compare

[cgarr]

I dont know how well the solder method really works on these heads since there is really no good flat spot to measure from? Whats wrong with just bolting the cylinder down, set to tdc and measure the gap? am I missing something? We are talking Deck height not valve / piston clearance right?

[mb911]

I guess the big thing is with a greater deck height the more likely to detonate

[Determined]

Nice timing, I was a bit confused about both measurements. It will be my project for this morning and I hope I don't have anything disappointing. I do have one question, the stock cylinder head gasket on my Carrera is .25mm, will increasing it to the 1mm gasket decrease compression and if so any ball park numbers? I'm running the Euro piston and cylinder set-up with higher compression and I'm starting to worry about detonation. I do have a back up plan and that is retard the timing and a Steve Wong chip, in addition I applied ceramic coating (thermal barrier coatings) to the dome of my pistons and a few other areas.

Thanks for your time and input.

Alex

[Jeff Alton]

Yes it will lower it. I just was screwing around with a CR calculator and will reduce it (95mm bore) in the area of about .5-.75 of a point. Note, that is approx.

Cheers

[ChrisBennet]

Originally posted by Determined
Nice timing, I was a bit confused about both measurements. It will be my project for this morning and I hope I don't have anything disappointing. I do have one question, the stock cylinder head gasket on my Carrera is .25mm, will increasing it to the 1mm gasket decrease compression and if so any ball park numbers? I'm running the Euro piston and cylinder set-up with higher compression and I'm starting to worry about detonation. I do have a back up plan and that is retard the timing and a Steve Wong chip, in addition I applied ceramic coating (thermal barrier coatings) to the dome of my pistons and a few other areas.

Thanks for your time and input.

Alex

Alex,
I assume you want to reduce the compression because you are afraid of detonation with your Euro pistons. Keep in mind that increasing the deck height by 1mm will increase the likelyhood of detonation - the opposite of what you want.

Obviously, reducing the compression enough and you won't have to worry about detonation. I just don't know where the break-even point is for reducing compression vs too large a deck height is. Does that make sense?

I think the Euro pistons are more likely to have seen detonation at some point already compared to US ones. Did you check/measure the ring lands? Those pistons may be worn out already.

-Chris

[Determined]

Hi guys,

Thanks for your feedback, I'm still a bit confused. A short while ago I posed my deck height results and I'm hoping to get some feedback. In summary, I used the solder approach and bolted a head on and torqued it properly to compress the solder. The solder before compression was about 3.20 mm, I used 1.0 mm cylinder base gaskets. After compression, the solder measured about 2.20 mm. Does this mean my deck height is 1.00 mm and if so am I too close to my valves? What does this do to my compression?

Thanks everyone for your time and input!

Best Regards,

Alex

[Eagledriver]

If you keep the 1mm base gasket you'll have 2.2mm piston to head clearance. This might be too much based on what others have said. It looks to me like you should use the .25 gasket taking your piston to head clearance down to 1.7mm That still sounds a little big but probably acceptable.

-Andy

[Determined]

Thanks again Andy,

I updated my other forum with new results using a .25 mm base gasket. In summary, I repeated the test with a new solder but this time using .25 mm base gaskets. The results were a 1.60 mm clearance, a little above the 1.50 mm recommended value but not bad. The method is very accurate and easy to perform. Thanks for your support!

Best Regards,

Alex

[Determined]

Andy,

A few more questions please, I checked every piston/cylinder yesterday and confirmed everything is near 1.60 mm piston to head clearance. However, I put two pieces of solder both horizontal to the crackshaft as indicated in Wayne's book but I got two way differen't results. It's pretty clear that this was due to the odd dome shape of the piston, left side was high and right side was low (at the horizontal point where solder was placed). My question is more on my second piece of solder that usually measured around 1.15 mm, is this a problem? How can I confirm that I will not hit my valves when they are open? Thanks for your time and input. Lastly, If what I'm really doing is measuring piston to head clearance then how do I measure my deck height on these weird shaped OEM Euro pistons?

Regards,

Alex